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Similarity and categorisation: neuropsychological evidence for a dissociation in explicit categorisation tasks

Roberson, Debi; Davidoff, Jules B. and Braisby, Nick. 1999. Similarity and categorisation: neuropsychological evidence for a dissociation in explicit categorisation tasks. Cognition, 71(1), pp. 1-42. ISSN 00100277 [Article]

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Abstract or Description

A series of experiments are reported on a patient (LEW) with difficulties in naming. Initial findings indicated severe impairments in his ability to freesort colours and facial expressions. However, LEW's performance on other tasks revealed that he was able to show implicit understanding of some of the classic hallmarks of categorical perception; for example, in experiments requiring the choice of an odd-one-out, the patient chose alternatives dictated by category rather than by perceptual distance. Thus, underlying categories appeared normal and boundaries appeared intact. Furthermore, in a two-alternative forced-choice recognition memory task, performance was worse for within-category decisions than for cross-category decisions. In a replication of the study of Kay and Kempton [Kay, P., Kempton, W., 1984. What is the Sapir-Whorf hypothesis? American Anthropologist 86, 65-78], LEW showed that his similarity judgements for colours could be based on perceptual or categorical similarity according to task demands. The consequences for issues concerned with perceptual categories and the relationship between perceptual similarity and explicit categorisation are considered; we argue for a dissociation between these kinds of judgements in the freesort tasks. LEW's inability to make explicit use of his intact (implicit) knowledge is seen as related to his language impairment.

Item Type:

Article

Identification Number (DOI):

https://doi.org/10.1016/S0010-0277(99)00013-X

Departments, Centres and Research Units:

Psychology

Dates:

DateEvent
1999Published

Item ID:

4945

Date Deposited:

21 Feb 2011 13:20

Last Modified:

30 Jun 2017 14:37

Peer Reviewed:

Yes, this version has been peer-reviewed.

URI:

http://research.gold.ac.uk/id/eprint/4945

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